DC1536A - Demo Manual

DEMO CIRCUIT DC1536
LTC6102-1
QUICK START
GUIDE
LTC6102-1
Precision Zero Drift Current Sense Amplifier
DESCRIPTION
Demonstration circuit 1536 is a General Purpose HighSide Current-Sense Amplifier featuring the LTC6102-1.
This demo board amplifies an on-board current-sense
resistor voltage-drop, providing a precision uni-polar
output voltage proportional to load current through the
sense resistor.
The demo circuit includes scaling resistors that program
the gain of the circuit to 33.3V/V. The LTC6102-1 is
powered from the same supply that the sense resistor is
connected to and provides a ground referenced output.
The LTC6102-1 can perform current measurements on
supplies ranging from 4V to 60V. Since the output voltage is a function of a controlled current through Rout,
ground-loop errors can be eliminated by simply locating
Rout at the destination point (subsequent signal process-
ing such as A/D conversion). Remote positioning of Rout
can be evaluated by simply removing the on board Rout
resistor (R3).
The key performance characteristics of the LTC6102-1
and DC1536 are shown in the Performance Summary
below. The LTC6102-1 is the same as the LTC6102 but
has an Enable feature at pin 3. On the Demo Board this
pin is pulled up by a 1MΩ resistor so the default setting
is the LTC6102-1 is Enabled.
Design files for this circuit board are available. Call
the LTC factory.
L, LT are registered trademarks of Linear Technology Corporation. Other product names
may be trademarks of the companies that manufacture the products.
PERFORMANCE SUMMARY Specifications are at TA = 25°C
SYMBOL
VIN
VMON
IMON
IOUT
IINQ
tR
PARAMETER
Monitored Supply Input Range
Measurement Output Signal
Measurement Output Signal (current mode)
Output Load Current Range
VIN Quiescent Current
VMON step-response time
CONDITIONS
MIN
4
IOUT = 10A
IOUT =10A, R3 removed
Thermal limit of RSENSE
VIN =12V, IOUT = 0A
IOUT step from 0A to 10A
TYP
5…48
2.0
400
MAX
60
12
230
4
UNITS
V
V
µA
A
µA
µs
OPERATING PRINCIPLES
The LTC6102-1 operates by amplifying the voltage drop
across a sense resistor placed in series with the power
source of the load to be monitored. The sense inputs of
the amplifier differentially measure the sense-resistor
drop to control an internal variable current source that
allows translation of the input information to a level referenced to V– (ground in this demo circuit). The circuit
gain is established by the ratio of the output resistor to
the input resistor and is essentially as accurate as the
resistors used. In DC1536 as shipped, the sense resistor
installed is 6mΩ and the resistor ratio sets the gain to
33.3V/V, so the nominal output scaling is 200mV per
Ampere of load current. Other scaling can be produced
by resistor replacement on the demo circuit.
The DC1536 Schematic diagram is shown in Figure 2.
1
LTC6102-1
QUICK START PROCEDURE
Demonstration circuit 1536 is easy to set up to evaluate
the performance of the LTC6102-1. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
1. With power off, connect the power supply positive to
IN and the common to GND. This supply should be in
the range of 4V to 60V. If this supply is not equipped
with an accurate current readout, a DMM (set to
measure Amperes) may be connected in series with
the supply as shown in Figure 1.
NOTE. Be sure that the current capacity of the DMM is adequate to
handle the intended load current. The Load Resistor must have the
appropriate power rating.
POWER
SUPPLY
10.
+ COM
2. Connect a voltmeter or oscilloscope probe to the MON
terminal, with the common connection or ground clip
tied to GND.
3. Connect a load to the OUT terminal (positive) and return (negative) to the common of the power supply.
The load may be a power resistor, active load instrument, or other circuit of interest.
4. Turn on the power supply.
5. Measure an output voltage that corresponds to the
load current. VMON = 0.2×IOUT for the factory installed
resistors.
1.0
0.2
DMM
DMM
A COM V
A COM V
LOAD
(10Ω)
Figure 1. Proper Measurement Equipment Setup
2
LTC6102-1
Figure 2. DC1536 Schematic Diagram
3